Astronomers discover youngest exoplanet to date

Astronomers have
detected the youngest exoplanet ever discovered, orbiting incredibly
close to a distant star. The discovery of the infant planet, known as
K2-33b, could allow astronomers to gain a clearer understanding of
the earlier stages of planetary formation.

Prolific planet-hunting
telescopes such as Kepler and Hubble have identified over 3,000 alien
worlds orbiting far-flung stars. The vast majority of these
exoplanets are discovered around stars that formed over a billion
years ago, meaning that the planets themselves are generally in the
mid-late stages of their lives.

Whilst the study of
these exoplanets has revealed a great deal regarding their evolution,
the relative absence of youthful planets such as K2-33b has prevented
astronomers from unravelling many of the mysteries that persist
regarding the early stages of planetary life cycles.

The orbit of K2-33b as compared to that of Mercury(Credit: NASA/JPL-Caltech)

K2-33b was first
detected as a periodic dip in light from its parent star, created as
the exoplanet passed between the stellar body and the Kepler Space Telescope. Follow up observations by the W. M. Keck Observatory,
Hawaii, and infrared data collected by the Spitzer Space Telescope
confirmed
that the system still plays host to a depleted protoplanetary disk,
meaning that planetary formation had, at least in astronomical terms,
only just concluded.

"Our Earth is
roughly 4.5 billion years old," states Trevor David of Caltech
in Pasadena, lead author of a study on the discovery. "By
comparison, the planet K2-33b is very young. You might think of it as
an infant." David is a graduate student working with astronomer
Lynne Hillenbrand, also of Caltech.

It is estimated that
K2-33b, which is believed to be slightly larger than Neptune, is
between 5-10 million years old, making it the youngest exoplanet
discovered to date. Data collected by the Earth and space-bound
observatories revealed that the exoplanet orbits very close to its
parent star, a characteristic that does not conform with current
theories on planetary formation.

Ordinarily, it is
thought that a body as massive and young as K2-33b should form in a
fairly distant orbit from its parent star, yet the newly discovered
exoplanet was observed 10 times closer than Mercury orbits from our
Sun. Astronomers are at a loss to explain the unusual orbit.

Much older planets had
been observed in ultra-close orbits, but the migration process is
thought to have taken hundreds of millions of years, and so could not
explain the orbit traversed by K2-33b. It is therefore possible that
the planet was simply created in its current orbit through some
process unaccounted for by the current models for planetary
formation.

A paper on the findings
has been published online in the journal Nature.